Algorithms that deal with the problem of service routing and wavelength assignment for off-line optimization of network utilization can be found. For example, there is significant body of academic research for the problem of Routing and Wavelength Assignment (RWA) in DWDM networks. Most of this research focuses on optimizing the wavelength utilization throughout the network. These solutions typically have very high computational complexity. Due to the complexity of such algorithms, providers typically use separate service planning and service provisioning systems. In other words, one drawback with existing approaches is that they typically result in reconfiguration of already provisioned services. As a result, these algorithms are mostly used in offline planning systems.
One such approach uses multiple transformed network graphs for computation of route and wavelength assignment. This dynamic routing and wavelength assignment approach addresses the assignment problem but requires multiple passes for each of the candidate route paths. For example, if there are forty (40) wavelengths in a given DWDM network, forty such graphs would be generated and shortest path route computations would be iteratively carried out for all forty graphs.
As stated before, there has been academic research on the Routing and Wavelength Allocation topic. The RWA algorithms broadly fall into two categories: Static and Dynamic Static RWA algorithms try to globally optimize the wavelength assignments with objectives of maximizing the number of services on a given network. These algorithms are not suitable for situations where demands need to be provisioned on an ongoing basis with minimal or no reconfiguration for existing services.
For automated service provisioning purpose, these approaches fall short in the following aspects. The approaches require reconfiguration/re-provisioning of existing services, and require multiple passes over routing and wavelength selection process. Also, these approaches require working and protection path routing and wavelength assignments to be computed independently and the approaches do not handle regeneration node computations or pre-specification. This is not desirable in most situations.